1. Field of the Invention
The present invention relates to an image-forming device that forms an image on a recording medium and, in particular, to an image-forming device which is provided with a plurality of scanner units and process units and which is also provided with a belt for image formation that conveys a developer image or a recording medium.
2. Description of Related Art
There has been proposed an image-forming device of a type that is provided with: an endless belt that conveys a developer image or a recording medium; a plurality of process units provided with a plurality of photosensitive drums for a plurality of colors so that each photosensitive drum faces the belt; a plurality of scanner units, each of which is for exposing and scanning the surface of the corresponding photosensitive drum to form an electrostatic latent image, which is developed by a corresponding process unit by using a developer of the corresponding color; and a transfer unit that transfers the developer image formed on the surface of each of the photosensitive drums, either onto the recording medium that is conveyed by the belt or onto the belt itself.
U.S. patent application Publication No. US2003/0147678A1 has proposed an image-forming device of a type, in which the belt is an intermediate transfer belt for supporting a developer. This type of image-forming device performs an image formation process in a manner described below.
When a scanner unit exposes and scans the corresponding photosensitive drum for one color in accordance with image data to form an electrostatic latent image, a corresponding process unit develops the electrostatic latent image by using a developer of the color. The developer image is transferred to the intermediate transfer belt by a transfer roller. Once developer images for all the colors have been superimposed thereon, the developer images are transferred to a recording medium.
Japanese Patent Laid-Open No. 7-234622 has proposed another type of image-forming device, wherein the endless belt is a conveyor belt for conveying a recording medium. In this type of image-forming device, developer images are superimposed directly onto a recording medium, while the recording medium is being conveyed by the conveyor belt, to form the superimposed images on the recording medium.